Syria says the Damascus government of embattled President Bashar al-Assad had accepted the cease-fire deal brokered by its Russian ally and the United States.

“A cessation of hostilities will begin in Aleppo for humanitarian reasons,” the Syrian news agency SANA said. Hours later, the Lebanon-based militant group Hezbollah, which is fighting alongside Assad loyalists, said it also would honor the cease-fire, while vowing to defend itself if attacked.

Turkey, which sent its military into the multisided conflict late last month, also announced support for the truce, which is to begin at sunset Monday.

The agreement was announced early Saturday in Geneva jointly by U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov.

U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov announced the agreement jointly in Geneva early Saturday.

Syrian opposition forces also said they welcomed the deal. However, since they feel neither Russian nor Syrian government forces adhered to earlier cease-fire plans, they said they doubted that a cease-fire could hold.

Moscow’s influence on Damascus “is the only way to get the regime to comply,” said a statement issued by Bassma Kodmani of the High Negotiations Committee of the Syrian Opposition.

Damage is seen near produce stands after airstrikes on a market in the rebel-controlled city of Idlib, Syria, Sept. 10, 2016.

Fighting rages despite deal

The complex and partly secret truce had little if any impact in or near war-ravaged Aleppo, as fighting raged and fatalities mounted Saturday.

An activist collective known as the Aleppo Media Center reported at least 45 people had been killed in rebel-held parts of the city, while the Britain-based Syrian Observatory for Human Rights placed the regional death toll at 69.

Beyond the cease-fire, the primary aim of the United States, the United Nations and nongovernmental groups active in Syria was arranging broader access for humanitarian aid to residents of the besieged city, once Syria's biggest population center, which has been cut off from outside help for months.

If there is “reduced violence” in Syria for seven consecutive days after the truce begins Monday, and if sufficient humanitarian aid is allowed into Aleppo, a senior U.S. State Department official said, “the two main events of this agreement start to take effect.”

With analysis and criticism of the conditions “going a little bit sideways” on social media, the senior U.S. official emphasized that “you’re not going to see calm in Syria anytime soon.”

If the Muslim Eid holiday, which begins at sunset Monday, is followed by a week of diminished violence, the United States and Russia are to begin coordinated airstrikes against the jihadist al-Nusra Front, as well as the so-called Islamic State group. And after those strikes get underway, the agreement then calls for the Syrian air force to cease all strikes against areas held by opposition forces. The regime's tactics throughout the conflict have produced heavy civilian casualty tolls.

Speaking Saturday, Kerry said Syrian government “air attacks have been the main driver of civilian casualties and migration flows and the most frequent violations of the hostilities."

“Halting all of the regime’s military air activities in key areas — key areas that are defined — should put an end to barrel bombs and indiscriminate bombing of civilian neighborhoods," Kerry said, adding that this would "change the nature of the conflict,” now more than 5½ years old.

Syria set to cooperate

Lavrov told reporters that Moscow had informed the Syrian government about the arrangements, “and it is ready to fulfill them.” Russia's top diplomat added that "no one can give a 100 percent guarantee" that the truce and other measures to follow will succeed, since there are forces in the region that will try to undermine the international agreement.

The United Nations’ special envoy for Syria, Staffan de Mistura, briefly joined Kerry and Lavrov at the podium in Geneva to welcome the U.S.-Russian agreement. He said it created a “real window of opportunity which all relevant actors in the region and beyond should seize, to put the crisis in Syria on a different path and reduce the violence and suffering of the Syrian people.”

Russia wants to see Syria's Assad stay in power, while moderate opposition forces and Turkey insist no transition deal can allow him to retain power for any period of time. The United States has long held that the Syrian leader cannot lead any future government, because of his brutal repression of all opposition throughout his time in power, long before the civil war broke out in early 2011.

U.S. Secretary of State John Kerry, center, and Russian Foreign Minister Sergei Lavrov, right, look at U.N. special envoy Staffan de Mistura during a joint press conference following their meeting to discuss the crisis in Syria, in Geneva, Switzerland, Sept. 9, 2016.

If the U.S.-Russian agreement holds, Kerry said, it could lead to political transition and reverse the current trend of "simply creating more terrorists, more extremists and destroying the country in the process.”

The Obama administration has repeatedly stated there is no military solution to the prolonged Syrian crisis, which has killed hundreds of thousands of Syrians and displaced 12 million people from their homes, according to U.N. estimates.

“Out of all this complexity is emerging now a simple choice between war and peace, between human agony and humanitarian relief, between the continued disintegration of an ancient society and the rebirth of a united and modern nation,” Kerry told reporters before flying back home.